Rheostat



Aug. 11, 1925. 7 1,549,416

T- W. HALLIDAY RHEOSTAT F1186 Oct, 23, 192:5

8 mvewto'o 35W My Patented Aug. 11, 1925.

UNITED STATES THOMAS VT. HALLIDAY, 0F RUPERT, IDAHO.

nnnosra'r.

Application filed October 23, 1923.

To all whom it may concern:

Be it known that THOMAS 1V. HALLIDAY, citizen of the United States, residing at Rupert, in the county of Minidoka. and State of Idaho, has invented certain new and useful Improvements in Rheostats, of which the following is a specification.

This invention relates to a rheostat and it has for its object to provide a device of simple and inexpensive construction adapted to controllably and accurately vary the strength of an electric current as delivered therethrough and further arranged in such way as to indicate the extent to which it has been adjusted and consequently indicate the strength of the current being delivered or to indicate the amount of resistance introduced into the circuit.

Further objects and advantages of the invention will be set forth in the detailed description which follows.

In the accompanying drawing:

Fig. 1 is a view looking toward one side of the rheostat;

Fig. 2 is a plan View of the rheostat;

Fig. 3 is a transverse vertical sectional view upon line 33 of F 2:

Fig. 4 is a front elevation of a graduated rotative head which coacts with a graduated bar as hereinafter described; and

Fig. 5 is a diagrammatic view of the windings upon the rotative drum of the rheostat.

Like numerals designate corresponding parts in all of the figures of the drawing.

Referring to the drawing it will be seen that the rheostat comprises an open frame consisting of plates 5 and 6 of insulating material, such as hard rubber, fiber or the like. These plates are connected by end plates 7 and 8. The end plate 7 carries a stationary rod 9 which is held to said plate by the lock nuts 10. A rotative and longitudinally adjustable sleeve 11 is slidably mounted upon said rod and is externally provided with a spiral rib 12 in the nature of a screw thread which engages in a boss 13 carried by the end plate 8. Thus when the sleeve 11 is rotated it is caused to travel longitudinally through said boss 13 which constitutes, in effect, a nut. The sleeve 11 carries a head 15 by which it may be rotated and the face of this head is graduated, as indicated at 16. In addition, the stationary rod 9 is longitudinally graduated, as indicated at 17. Thus a coarse or approximat adjustment of the position of the sleeve 11 Serial ITO. 670,354.

may be effected and determined by the graduations 17 and finer or intermediate adj ustments may be determined by the scale 16.

The sleeve 11 carries upon its inner end a drum 18 of insulating material, said drum and metallic end plates 19 and 20 therefor rotating bodily with the sleeve. The periphery of the drum is provided with a pair of spiral grooves 21 and 22. The showing in Fig. 5 is intended to indicate there are two distinct windings of wire .3 and 2% disposed in said grooves. A block 2% of insulating material has the contact bars 25 and 2-6 pivotally connected thereto at 27 and 28 and the free ends of these bars are connected by a spring 29, insulated at 29 which tends to draw said bars together and to thrust the inner, edges of said bars into engagement with the windings 23 and 2%, respectively.

The pivot points 27 and 28 of the arms 25 and 26 constitute the binding posts of the rheostat, as indicated at 30. It is manifest that by turning the head 15, rotation will be imparted to the drum and that by reason of the spiral nature of the threads 12 the drum will be caused to travel longitudinally of the frame while at the same time the contact bars 25 and 26 will be kept in engagement with the windings 23 and 2 1, since these bars are drawn into the spiral grooves of the drum by the action of the spring 29. The said windings 23 and 24 are connected with each other by a bight portion 22 at the lefthand end of the drum. Thus if the drum be caused to move toward the left in 2, it is manifest that more of the wire winding must be traversed by the current in order for it to pass from one of the contact bars to the other and thus, to this extent, the resistance to the passage of the current is increased and the strength of the current ultimately delivered is decreased.

Furthermore it will be observed that the extent of this adjustment of the drum will be accurately reflected by the position of the head 15 with respect to the circumferential graduat-ions 17 on the rod 9 and by the position of the graduations 16 upon said head with respect to the longitudinal graduation 17 upon the rod. The parallel arrangement of the windings provides a noninductive circuit so that accurate measurement of alternating current circuits is rendered possible. Furthermore the arrangement of the graduations on the head 15 and rod 9 renders it possible to secure definite readings of the resistance of the windings at any point in the drum either directly or by means of a calibration curve.

Having described my invention what I claim is:

1. A device of the character described comprising a longitudinally movable drum, a double spiral conducting element upon the surface thereof, having its two parts in physical parallel relation, opposed contact bars engaged with said elements and means for maintaining said bars in contact with said elements during the longitudinal movement of the drum.

2. A device of the character described comprising a longitudinally movable drum having a double spiral groove in its face and a double spiral conducting member in said groove having its two parts in physical parallel relation, a contact bar having its edge engaged in said groove and with said conducting member, and spring means tending to draw said contact bar into said groove.

The combination with a supporting frame, of a member threaded therein, a drum carried by said member, said drum having a pair of double spiral grooves in its periphery and having connected parallel wire windings in said grooves, a pair of opposed contact bars, one upon each side of said drum the inner edges of which engage said wires and spring means engaged with the free ends of said contact bars and tending to draw them together and into engagement with said wires.

a. A device of the character described comprising a supporting frame, a fixed rod therein, a sleeve upon said rod having threaded engagement with a part of said frame whereby endwise movement is imparted to the sleeve when said sleeve is rotated, a drum carried by said sleeve having 1,5aaa1e a pair of spiral grooves in its periphery and having spiral windings of wire in said grooves and a pair of opposed contact arms pivoted at one of their ends and spring means engaged with the other of the ends of said contact bars and tending to draw them together.

A structure as recited in claim 4: wherein said sleeve and rod are provided with coact-ing graduations.

6. A structure as recited in claim 4L wherein said rod is provided with longitudinally spaced graduations, a head upon the sleeve and radial graduations upon said head.

7. A device of the character described comprising a longitudinally movable drum, a conducting element upon the surface thereof in the form of a double spiral the two parts of which are in physical parallel relation and contact bars lying in engagement with adjacent convolutions of the spiral conducting element during the movement of the drum.

8. A device of the character described comprising a coil carrying element and a contact element one of which is movable with respect to the other, a rotative threaded member by which movement is imparted to the movable element, radial Vernier graduations carried by the rotative member and a fixed element graduated along its length for indicating the longitudinal adjustment of the rotative member and carrying a circumferential graduation which coacts with the radial graduations of the said rotative member.

In testimony whereof he aflixes his signature.

THOMAS WV. HALLIDAY.

.Vitnesses J. MURPHY, H'. A. BAKER. 

